As solid-state imaging devices for capturing color images, single-plate type imaging devices such as a complementary metal oxide semiconductor (CMOS) type, a charge coupled device (CCD) type, and the like are conventionally known. As described in JP-A-2007-180157 (corresponding to US2007/0145241A1), for example, these solid-state imaging devices are structured such that a plurality of photodiodes, i.e., photoelectric conversion elements, are formed at the surface portion of a semiconductor substrate in the form of a two-dimensional array, a light shielding film is laminated thereon, openings enabling the incidence of light upon the photodiodes are provided at those portions of this light shielding film that face the photodiodes, and color filters are respectively overlaid thereon.
As the color filters, there are many cases where the three primary colors of red (R), green (G), and blue (B) are used. A color filter of green (G) is overlaid on about half of the plurality of photodiodes formed in the two-dimensional array, a color filter of red (R) is overlaid on a half of the remaining half, and a color filter of blue (B) is overlaid on the remainder. The color filters of the respective colors are respectively arrayed so as to be averagely scattered over the entire light receiving surface of the solid-state imaging device.
In the above-described conventional solid-state imaging device, one light shielding film opening corresponds to one photodiode, and the color filter of one color corresponds to one light shielding film opening. For this reason, approximately two-thirds of the light incident upon one photodiode is absorbed by the color filter (for example, blue light and green light incident upon the red color filter are absorbed and converted to heat), so that, in principle, there is a problem in that the light utilization efficiency is low.
In addition, an optical image of an object formed on the light receiving surface of the solid-state imaging device is subjected to sampling and converted to electrical signals by the respective photodiodes. In the above-described conventional structure, however, since a sampling point of red, a sampling point of green, and a sampling point of blue are all different, signal processing is required in which detection signals of green and blue at the sampling point of red are determined by performing the interpolation calculation of signals obtained from circumjacent sampling points of green and blue. Hence, there is another problem in that a decline in the quality of the captured image due to the positional offset of sampling points is, in principle, unavoidable.